In recent years, an enhancement in the function of the device has lead to a change in the structure for mounting a device on a circuit board from a structure, for mounting a device, utilizing through-holes provided in the circuit board to PGA (pin grid array) having a large number of terminal pins on the bottom of a chip, QFP (quad flat package) wherein connection terminals are protruded around a device, PLCC (plastic leaded chip carrier), and other structures.
At the present time, a structure, for mounting a device, called BGA (ball grid array) having connection solder balls provided on the bottom of the device is widely known in the art.
A conventional structure for mounting a device on a circuit board comprises a semiconductor device having an array of solder balls on a back surface, and a printed circuit board having an array of terminals on a top surface, wherein each of the solder balls is connected to a corresponding one of the terminals in accordance with the solder-reflow process.
In the conventional structure for mounting a device on a circuit board, however, there are disadvantages in that once the device is mounted on the circuit board, the device cannot be separated from the circuit board, making it impossible to repair or replace the device, and in that, since the device is constructed so as to cover the terminals of the circuit board, a wiring pattern to be connected to the terminals cannot be lead onto the mounting surface of the circuit board, so that signals for the evaluation of the performance of the device or the test of the device cannot be input into and output from the device.